Cytopathology in focus: Abnormal cervical screening tests: a personal approach

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Surveillance following HSIL treatment and hysterectomy. The guidelines recommend that individuals with a hysterectomy who have had HSIL (CIN2 or 3), AIS, or cancer continue to have HPV-based testing every three years for at least 25 years; this mirrors the guideline for surveillance in individuals treated by excision. Any person treated for HSIL should have more intense (six-month and then three annual) HPV-based surveillance tests.

Age over 65. Although women over 65 may generally exit cervical cancer screening programs, those who have a history of CIN2+, AIS, or cancer should continue surveillance screening as long as the person is in reasonable health, following the preceding guidelines. The recommended management for abnormalities follows the aforementioned guidelines. Data on screening in this age group is limited, but there is sufficient evidence of a higher rate of cervical cancer in individuals over age 65^6-7 to warrant extending screening beyond that age. If an individual without a history of cervical abnormality is screened beyond age 65, the preceding clinical management recommendations apply.

Primary HPV screening. Another major change from past guidelines is the recommendation to add an additional triage test, currently the Pap test, for all HPV-positive tests from primary HPV screening only, including those that are HPV16+ or HPV18+. If the primary HPV screening test is HPV16/18+ and a triage test is not feasible, the individual is referred to colposcopy, and a triage test is recommended at that time. Colposcopy and biopsies or expedited treatment are recommended for all HPV16+ or HPV18+ patients due to the high risk of CIN3+ in this cohort.

The intention is to improve specificity to allow for more effective patient triage. Pap tests will serve as a reflex test following a positive HPV result to determine which patients to refer to colposcopy. Adding a Pap test potentially provides information on the degree of precancer and can direct decisions on expedited treatment without biopsies. For example, the immediate risk of CIN3 in those who are HPV16+ and have HSIL on Pap tests exceeds the treatment threshold of 60 percent. In the future, it is possible that additional ancillary tests that enhance Pap test interpretation or rely on molecular methods will become acceptable for triage.

Rare Pap test results and Pap test adequacy. Rare findings on Pap tests are difficult to fit into guideline recommendations, and data on their significance and appropriate follow-up is often minimal. One exception is the area of atypical glandular cells (AGC)/adenocarcinoma in situ (AIS), which has been widely studied over several decades. The problem with most studies of AGC is that morphologic criteria are poorly reproducible; cells may be of squamous, endocervical, or endometrial origin; and confirmatory biopsies are sometimes unavailable, making comparisons difficult. Conversely, AIS and AGC-favor neoplasia are associated with very high risk of precancer or invasion, regardless of HPV results,⁸ prompting the following recommendations.

Atypical glandular cells/adenocarcinoma in situ. Colposcopy with endocervical sampling is recommended for all Pap test results of AGC and AIS (despite qualifying terms such as “not otherwise specified” or “favor neoplasia”), regardless of HPV status, except for patients who are pregnant. Triage using HPV testing is not recommended, and triage with repeat Pap tests is unacceptable. If the patient is 35 years or older, or has increased risk for endometrial neoplasia (such as vaginal bleeding), then endometrial sampling is also indicated. If the Pap test is qualified as “atypical endometrial cells,” then initial biopsies of the endometrium and endocervix are preferred, but initial colposcopy is also acceptable. Colposcopy is recommended when endometrial and endocervical sampling is negative.

Subsequent surveillance recommendations for AGC without detected disease includes cotesting at 12 and 24 months, and if negative, cotesting at three years. Colposcopy is recommended for any abnormal results. For patients with Pap test reports of atypical glandular cells, favor neoplasia (AGC-N) or AIS without invasive disease detected on colposcopy and biopsy, a diagnostic excisional procedure is recommended, along with endocervical sampling.

Lack of transformation zone on Pap test. Patients 21 to 29 years of age who have a negative for intraepithelial lesion or malignancy (NILM) result may proceed with routine screening; it is unacceptable to use HPV testing as a triage test in these patients if the original intention was primary screening. For those ages 30 and older who have a NILM Pap test, insufficient transformation zone, and no or unknown HPV testing, HPV testing is preferred, but the Pap test may also be repeated in three years without HPV testing.

Review of recent studies found no adverse effect of the absence of a transformation zone on the detection of precancer.

Benign endometrial cells or benign glandular cells in post-hysterectomy individuals. Guidelines recommend that postmenopausal women with endometrial cells on Pap test have an endometrial biopsy. Post-hysterectomy individuals with benign glandular cells require no further evaluation, and no additional testing or surveillance is necessary for premenopausal individuals with benign endometrial cells, stromal cells, or histiocytes on Pap tests.

Unsatisfactory Pap test. Individuals with an unsatisfactory Pap test (with or without HPV testing) should have a repeat age-based screening test in two to four months, similar to prior guidelines, and using HPV testing to determine triage after an unsatisfactory Pap test is not recommended. For patients 25 years and older with an unsatisfactory Pap and positive HPV cotest, repeating the Pap test in two to four months or referral to colposcopy is acceptable. Colposcopy is recommended if genotyping reveals HPV16 or 18.

Management of histology results. The guidelines recommend that treatment decisions be made with patients and with regard for future cancer risk, childbearing risks, and personal preferences. The preferred management for histologic HSIL (CIN2 or CIN3) remains treatment, unless the patient is pregnant, but observation for CIN2 is acceptable if the patient has concerns about future pregnancy. Excisional therapy (LEEP, cold-knife cone, or laser cone) is preferred but ablation (cryotherapy, laser ablation, or thermoablation) is acceptable as long as the squamocolumnar junction is fully visualized, the lesion does not extend into the canal, and the endocervical sampling is not positive for CIN2+.

For CIN1 histology preceded by an HSIL Pap test, either a diagnostic excision or observation with colposcopy and HPV-based testing at one year is recommended. If CIN1 is preceded by an ASC-H result, observation at one and two years with HPV-based testing is recommended, and if an HSIL Pap test is reported or ASC-H persists at two years, diagnostic excision is recommended.

For individuals age 25 and older with persistent CIN1 (beyond two years), continual observation is preferred but treatment is acceptable. Those under age 25 should continue with observation.

Hysterectomy remains the preferred treatment for biopsy-proven AIS, but initial excisional procedure is recommended to exclude invasion, even if a hysterectomy is planned. Fertility-sparing procedures are acceptable if margins are negative and the patient can adhere to close surveillance.

How will these changes affect the laboratory? Currently, the two HPV testing platforms that the FDA approved for primary HPV tests in cervical cancer screening in individuals age 25 and older are the Cobas HPV Test (Roche) and BD Onclarity HPV Assay (Becton Dickinson). All other HPV testing platforms can be used for cotesting, reflex, surveillance, or follow-up testing, but their use is discouraged in primary HPV screening until FDA approved or further information about their safety is established. HPV RNA testing (Hologic Aptima) should be used in conjunction with Pap tests (cotesting) until more data become available. None of the current HPV platforms has FDA approval for testing vaginal specimens for any purpose, and laboratories doing so must validate their HPV platform for vaginal samples. Because most clinicians are unaware of federal regulatory requirements for instrumentation and testing platforms, laboratories should provide clear guidance and terminology on requisitions that permit users to distinguish primary HPV test orders from surveillance and reflex tests. Laboratory requisitions and online order entry options should be evaluated to determine if they are compliant with new management and screening guidelines.

The consensus process participants also considered the laboratory impact of proposed changes and addressed the recent CAP-ASCCP Lower Anogenital Squamous Terminology (LAST) project recommendations⁹ for lower anogenital tract pathology reporting and the use of p16. In recognition of the overuse of p16 and potential overdiagnosis of CIN2, 3 on surgical specimens,¹⁰ recommendations emphasize the judicious use of p16 to support a morphologic impression of CIN2,3, but they discourage upgrading a morphologic CIN1 based on a positive p16.

Although the LAST project advocates the use of “squamous intraepithelial lesion” terminology for surgical pathology as opposed to “cervical intraepithelial neoplasia,” it currently recommends qualifying all HSIL surgical results with the qualifier -CIN2 or -CIN3 to improve future epidemiologic studies and tailor clinical management. The low rate of progression of CIN2 allows for longer surveillance intervals rather than requiring excision, thereby reducing the risk of cervical incompetence in younger women with this lesion.^11,12 Current recommendations allow for more conservative management of individuals under age 25 using observation only.

1. 1. Perkins RB, Guido RS, Castle PE, et al. 2019 ASCCP risk-based management consensus guidelines for abnormal cervical cancer screening tests and cancer precursors. J Low Genit Tract Dis. 2020;24(2):102–131.
   2. Egeman D, Cheung LC, Chen X, et al. Risk estimates supporting the 2019 ASCCP risk-based management consensus guidelines. J Low Genit Tract Dis. 2020;24(2):132–143.
   3. Wentzensen N, Massad LS, Mayeaux EJ Jr, et al. Evidence-based consensus recommendations for colposcopy practice for cervical cancer prevention in the United States. J Low Genit Tract Dis. 2017;21(4):216–222.
   4. Committee on Practice Bulletins–Gynecology. Practice bulletin No. 168: cervical cancer screening and prevention. Obstet Gynecol. 2016;128(4):e111–e130.
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   8. Zhao C, Florea A, Onisko A, Austin RM. Histologic follow-up results in 662 patients with Pap test findings of atypical glandular cells: results from a large academic womens hospital laboratory employing sensitive screening methods. Gynecol Oncol. 2009;114(3):383–389.
   9. Darragh TM, Colgan TJ, Cox JT, et al. The Lower Anogenital Squamous Terminology Standardization Project for HPV-associated lesions: background and consensus recommendations from the College of American Pathologists and the American Society for Colposcopy and Cervical Pathology. J Low Genit Tract Dis. 2012;16(3):205–242.
   10. Castle PE, Adcock R, Cuzick J, et al. Relationships of p16 immunohistochemistry and other biomarkers with diagnoses of cervical abnormalities: implications for LAST terminology. Arch Pathol Lab Med. 2020;144(6):725–734.
   11. Silver MI, Gage JC, Schiffman M, et al. Clinical outcomes after conservative management of cervical intraepithelial neoplasia grade 2 (CIN2) in women ages 21-39 years. Cancer Prev Res. 2018;11(3):165–170.
   12. Moscicki A-B, Ma Y, Wibbelsman C, et al. Rate of and risks for regression of a cervical intraepithelial neoplasia 2 in adolescents and young women. Obstet Gynecol. 2010;116(6):1373–1380.

   Dr. Crothers is associate professor of pathology practicing subspecialty gynecologic, breast, and cytopathology consultation at the Joint Pathology Center, Silver Spring, Md. She is a former chair and former member of the CAP Cytopathology Committee. Dr. Davey is professor of pathology and associate dean at the University of Central Florida, Orlando. She practices pathology at the Orlando VAMC and is a former CAP Cytopathology Committee member.